Merge pull request #56 from volkov0aa/master

Prefer to use icons from system icon theme
build fixes: build options moved into the beginning of main cmake file;link directories for enca when it's located in non-standard path
main window restore: use save/restore geometry methods instead setGemotery/geometry as the original solution does not work correctly on OS X (and wayland probably); unused MW event handlers commented out
QDirModel replaced by much (and I mean really much) faster QFileSystemModel; fm plugin: fixed #57 Option to show hidden files
fm: useless slot/icon removed
fm: saved file tree sorting
Added per-document indentation settings and indentation auto-detect.

Auto-detect executes automatically when loading files.
Minor code cleanup.
Made auto-detect-indentation feature optional in editor settings.
Improved indentation auto-detection and made it enabled by default.

Also updated the Editor settings layout to better communicate the
slightly changed meanings of some of the options.
Merge branch 'master' of https://github.com/Mezomish/juffed
Merge pull request #59 from cessen/master

Merged Per-document indentation settings